DETROIT -- A security guard called police before dawn Thursday, watching in disbelief as a convoy of stolen 2018 Ram trucks crashed through the gate at the Fiat Chrysler factory where they had been made.

Trucks fresh off the assembly line.

They headed south on Mound Road in the Detroit suburb of Warren, Mich., -- and disappeared.

"This was well planned," said Warren Police Commissioner Bill Dwyer. "They were able to take at least 10 or 11 Ram trucks out on a convoy."

The crime was reported at 3:55 a.m. Dwyer said preliminary reports were that the thieves came to the plant in another Ram — a 2003 pickup stolen from a Warren home. They cut a hole in the chain link fence and unloaded up to a dozen drivers who ran to the new vehicles, undetected until it was too late, and drove away.

"They probably had 10 people in that bed," Dwyer said. "Then they abandoned it where they cut the hole."

Twelve hours after the theft, Fiat Chrysler was still doing an inventory, working to figure out the vehicle identification numbers, the colors of vehicles stolen and exactly how many trucks were gone.

"They couldn't tell us for sure," Dwyer said. "They're conducting an audit to determine how many. They have their own surveillance team. We're waiting for them to report back to us."

Fiat Chrysler declined to confirm whether keys were stored with the vehicles parked on the lot, noting that security is an ongoing issue that requires confidentiality.

"The company will be assessing security measures at the location and implementing any necessary changes to prevent future incidents," spokeswoman Jodi Tinson said Thursday afternoon.

Law enforcement will be looking for surveillance video along Mound Avenue and throughout the area.

Theft of the new Rams from a secure lot north of Detroit was likely an orchestrated effort meant to fill an order for stolen vehicles, theft experts said.

"We're calling it the mass-order business," said Mark Wagenschutz, executive director of HEAT, an independent Michigan agency funded by the insurance companies to help eliminate auto theft. "People think it's a Detroit problem. This is a statewide issue."

At issue is whether the target is the vehicle itself or some expensive item inside the vehicle, such as the stereo system or the navigation system, he said.

"Several parts of the Ram are in high demand," Wagenschutz said. "You don't know if they wanted the Ram or pieces. They'll have to get off site before they can lift the hood and take things out."

Ram ranked third among all vehicles sold in 2017, behind Ford F-Series trucks and Chevrolet Silverados. The bestselling F-Series sold 896,764 while Silverado sold 585,864 and Ram sold 500,723.

The new Ram is a popular vehicle with prices of $30,000 or more, with 143,216 sold in the U.S. already in 2018.

Chris McGoey, a Los Angeles-based security expert, assumed the trucks would have been loaded onto a carrier and hauled off.

"All these things took days, weeks, months of planning," he said. "Once you get the vehicles, you've got to have a buyer. This definitely sounds like an order. Sounds like kind of theft where immediately could be taken to a port, put into a container and shipped offshore."

Apart from vehicle thefts, investigators said they are seeing more parts stolen from new vehicles — especially expensive wheels and rims, Wagenschutz said.